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How to test lead hardness. Many people use a 1" steel ball bearing. Not critical.
The instructions are from the Corbin website.
Here is a simple way to test the Bhn number of unknown lead samples: all you need is a caliper, two bottle caps, a vise, a 5mm diameter (aprox. size) ball bearing, and a known pure sample of lead (Corbin can furnish pure lead of 99.995% Pb with trace silver).
Melt enough lead to fill one bottle cap with unknown sample, and the other with known pure lead. Make sure the surface is smooth and flat when the lead hardens and cools.
When the lead is cold, put the ball bearing between the two lead surfaces and squeeze this "sandwich" in the vise until the ball is driven partly into both surfaces (just enough to make a fair sized dent, but not past the middle of the ball).
Remove the sandwich and measure the two dent diameters. First measure the known pure lead dent and write down this number. Then measure the dent diameter in the unknown lead sample and write it down. Square both numbers (multiply times themselves). Then divide the resulting square of the unknown lead dent diameter into the square of the known pure lead dent diameter. This could be written as (L times L) divided by (X times X) where L is the pure Lead dent diameter, and X is the unknown lead dent diameter.
The answer should be a number of 1 or greater. If it is a fraction, or less than 1 in value, you have inverted the two dents and divided the wrong way. In that case, try again. When you get an answer that is 1 or greater, multiply it by 5. This is the actual Brinnell Hardness Number of the unknown sample.
Here is the formula:
H = 5 * (D1^2)/(D2^2)
...where H is the hardness of the unknown sample in Bhn number, D1 is the diameter of the indentation formed in the known pure lead sample, and D2 is the diameter of the indentation in the unknown hardness sample.
The instructions are from the Corbin website.
Here is a simple way to test the Bhn number of unknown lead samples: all you need is a caliper, two bottle caps, a vise, a 5mm diameter (aprox. size) ball bearing, and a known pure sample of lead (Corbin can furnish pure lead of 99.995% Pb with trace silver).
Melt enough lead to fill one bottle cap with unknown sample, and the other with known pure lead. Make sure the surface is smooth and flat when the lead hardens and cools.
When the lead is cold, put the ball bearing between the two lead surfaces and squeeze this "sandwich" in the vise until the ball is driven partly into both surfaces (just enough to make a fair sized dent, but not past the middle of the ball).
Remove the sandwich and measure the two dent diameters. First measure the known pure lead dent and write down this number. Then measure the dent diameter in the unknown lead sample and write it down. Square both numbers (multiply times themselves). Then divide the resulting square of the unknown lead dent diameter into the square of the known pure lead dent diameter. This could be written as (L times L) divided by (X times X) where L is the pure Lead dent diameter, and X is the unknown lead dent diameter.
The answer should be a number of 1 or greater. If it is a fraction, or less than 1 in value, you have inverted the two dents and divided the wrong way. In that case, try again. When you get an answer that is 1 or greater, multiply it by 5. This is the actual Brinnell Hardness Number of the unknown sample.
Here is the formula:
H = 5 * (D1^2)/(D2^2)
...where H is the hardness of the unknown sample in Bhn number, D1 is the diameter of the indentation formed in the known pure lead sample, and D2 is the diameter of the indentation in the unknown hardness sample.
Best method, been around forever: drop an one pound ingot on a concrete floor,
if it rings its hard, if it thuds is soft
if it rings its hard, if it thuds is soft
I have close to 2,000 pounds of lead from over a dozen sources. Just picked up 150 pounds of Linotype. All the above suggestions do work. I posted somewhere about using weight and volume to come up with a density. Most of these except the dropping may require melting. Really would like to find a hardness tester.
Still interested in a hardness tester if you read this. I also bought the drafting pencil set and tested a bunch of lead for hardness. Started a post under reloading to document my path.
